Hi, i got my first betta 3 days ago and he has been just fine until this morning. He has ragged fins and there is nothing in the tank that is likely to have attacked him (I currently have neon tetras, cory cats,and a bristlenose plec-the rest of my fish were sent to an early grave by a very aggressive golden gourami who has now gone back to my lfs) so i can only assume its fin rot. What is the best way to treat him? I was windering if i should put him into quarantine tank (though i have no filter with it) and treat him with a shop bought medicine?any advice? thanks